1. Field of Invention
The invention relates to a display encapsulation apparatus and method for encapsulating a display and, in particular, to a flat-panel display (FPD) encapsulation apparatus and method for encapsulating an FPD.
2. Related Art
Accompanying the development of electronic technology, displays have become lightweight and high efficiency, and are wildly spread. The dimensions of displays have decreased, especially flat-panel displays (FPDs) such as liquid crystal displays (LCDs) and organic light-emitting displays (OLEDs). OLEDs possess the advantages of self-emissive, full viewing angle, high power efficiency, easily manufactured, low cost, rapid response, and full color. Hence, OLEDs are rapidly becoming a major choice for flat panel display technology in the future. Those skilled in the art should know that OLEDs utilize the self-emissive properties of certain organic functional materials to achieve the object of display.
In general, an FPD is consisting of an electroluminescent substrate and a glass substrate. With reference to FIG. 1, an encapsulation process for binding the electroluminescent substrate and glass substrate includes the following steps of: providing a glass substrate (step 101), applying a adhesive on the glass substrate (step 102), providing an electroluminescent substrate (step 103), and pressing the glass substrate and electroluminescent substrate to bind the glass substrate and electroluminescent substrate (step 104).
The above mentioned encapsulation process is performed in an FPD encapsulation apparatus. Referring to FIG. 2A, a conventional FPD encapsulation apparatus 2 includes a chamber 21, a curing device 22, and a pressing mechanism 23. The chamber 21 has an airtight space, which is filled with inert gas to decrease moisture and oxygen. Thus, the electroluminescent substrate could be prevented from the moisture and oxygen, and have improved durability. The curing device 22 includes a supporting portion 221 and an UV light source 223. The supporting portion 221 is a quartz plate and is used to support the glass substrate. The UV light source 223 is located under the supporting portion. The pressing mechanism 23 is provided opposite to the curing device 22. One end of the pressing mechanism 23 is located in the chamber 21 and is movable. The electroluminescent substrate is attached to this end of the pressing mechanism 23, and is also movable in the chamber 21.
Referring to FIG. 2B, in step 101, a glass substrate 31 is placed on the supporting portion 221. In this case, a robot arm (not shown) is usually used to transfer the glass substrate 31 into the chamber 21, and the glass substrate 31 is positioned on the supporting portion 221.
With reference to FIG. 2C, in step 102, a dispensing mechanism (not shown) is employed to apply an adhesive 32 on the glass substrate 31. The adhesive 32, which is usually made of epoxy, is formed as a closed loop or frame or has a gap for air venting. As shown in FIG. 3A, the adhesive 32 is formed as a closed loop or frame on the glass substrate 31 to surround a portion of the FPD to be protected. As shown in FIG. 3B, the adhesive 32 is formed on the glass substrate 31 with one gap 321 or more. Thus, when pressing the glass substrate and/or electroluminescent substrate to bind the substrates, gas positioned between the substrates can be vented out through the gap 321. The gap 321 may then be closed during pressing the substrates.
Alternatively, the adhesive 32 can be dispensed on the glass substrate 31 with an additional dispensing apparatus. The glass substrate 31 with the adhesive 32 is then moved into the chamber 21 and positioned on the supporting portion 221. After the glass substrate 31 with the adhesive 32 is positioned on the supporting portion 221, the UV light source 223 emits an UV light beam. The UV light beam passes through the supporting portion 221 and the glass substrate 31, and then pre-cures the adhesive 32.
As shown in FIG. 2D, in step 103, the electroluminescent substrate 33 is attached to one end of the pressing mechanism 23. In this case, an additional robot arm is employed to move the electroluminescent substrate 33 into the chamber 21 and position the electroluminescent substrate 33 at one end of the pressing mechanism 23. This end of the pressing mechanism 23 is a suction plate for holding the electroluminescent substrate 33. In addition, this end of the pressing mechanism 23 can be a chuck for chucking the electroluminescent substrate 33.
Referring to FIG. 2E, in step 104, the pressing mechanism 23 moves down to press the glass substrate 31 and/or the electroluminescent substrate 33, and the glass substrate 31 and electroluminescent substrate 33 are then bound to each other via the adhesive 32. In this case, the electroluminescent substrate 33 aligns with the glass substrate 31 in advance, and the pressing mechanism 23 then moves by a screw or a pneumatic system. Before the glass substrate 31 and the electroluminescent substrate 33 are bound, the chamber 21 may be filled with inert gas so as to prevent moisture and oxygen from being encapsulated between the glass substrate 31, adhesive 32, and electroluminescent substrate 33.
After the glass substrate 31 and electroluminescent substrate 33 are bound, an UV light source 223 emits an UV light beam passing through the supporting portion 221 and glass substrate 31 to cure the adhesive 32.
During the encapsulating process of the glass substrate 31 and the electroluminescent substrate 33, the adhesive 32 is pressed, resulting in that the space between the glass substrate 31, adhesive 32, and electroluminescent substrate 33 decreases. Thus, the pressure of the space increases accordingly. In particular, when performing high temperature test, the residual gas in the space will be heated and expand. As a result, the pressure of the space becomes larger, which destroys the encapsulated structure of the glass substrate 31, adhesive 32, and electroluminescent substrate 33. Therefore, the durability of the FPD decreases.
In addition, during the process of pressing the glass substrate 31 and electroluminescent substrate 33, the space between the glass substrate 31, adhesive 32, and electroluminescent substrate 33 becomes smaller and smaller. Thus, the gas in the space may be vented out through the adhesive 32, resulting in bubbles or worm holes in the adhesive 32. The worm holes are the moving traces of the bubbles. Accordingly, the adhesive 32 may not stop the external moisture and oxygen properly. In other words, the external moisture and oxygen may facilely pass through the adhesive 32 having worm holes or bubbles, and the manufactured FPD will be damaged.
Since the adhesive 32 usually contains volatile materials, such as organic solvents, the volatile materials may be released from the adhesive 32. The FPD may suffer from the volatile materials. For example, the volatile materials may destroy the organic functional materials of the electroluminescent substrate 33. Thus, the dark spots of the FPD occur, and the durability of the FPD decreases.
Therefore, it is an important subjective of the invention to provide an FPD encapsulation apparatus and encapsulating method to control the pressure of the space between the glass substrate 31, adhesive 32, and electroluminescent substrate 33, and to avoid the bubbles or worm holes in the adhesive 32. Furthermore, the residual volatile materials, which include harmful gas, can be removed.